Lake Terrell Dam Channel Restoration and Fish Passage Project

History of Lake Terrell

The area now known as Lake Terrell was once a vast area of beaver dam impounded wetlands that Native Americans frequented for elk, deer and beaver hunting. The wetlands and Terrell Creek tributaries also supported large numbers of coho salmon. The area was purchased by the Washington State Department of Fish & Wildlife (then the Dept. of Game) in the 1940s for waterfowl habitat restoration and public recreation. The Lake Terrell Dam was constructed in 1950 to enlarge the Lake and stabilize the water levels to maximize waterfowl opportunities. The dam also blocked fish passage into Lake Terrell and upstream tributary streams and prevented good summer stream flows below the dam.

Lake Terrell and Terrell Creek Today

500 acre Lake Terrell is now part of the Washington Department of Fish and Wildlife’s Whatcom Wildlife Area. 1,500 acres make this a popular destination for waterfowl hunters, upland bird hunters and fishing enthusiasts. Resident fish species include largemouth bass, channel catfish, triploid rainbow trout, perch, sunfish and bullheads. Terrell Creek downstream from Lake Terrell and Butler Creek upstream from Lake Terrell are unique because they have largely intact riparian areas. The riparian area consists of trees, shrubs and other native plants that are essential for a stream corridor to function well and support native fish and wildlife species.

Dam Reconstruction and Stream Flow Supplementation

The Lake Terrell Dam was originally constructed in 1950 and consisted of concrete headwalls and three sections of wooden stop logs that could be removed to adjust water levels. Reconstruction included replacing the wood stop logs with concrete panels topped by a V notch weir designed to supplement summer stream flows. Lake water will be metered out slowly through the weir keeping flow in Terrell Creek during the dry summer months.

Stream Channel Restoration and Fish Passage

Fish passage was restored over the Lake Terrell dam by reconstructing over 600 linear feet of Terrell Creek below the dam. The previously dredged stream channel was filled with over 2,300 tons of hardpan fill material and topped with almost 500 tons of spawning gravels. The hardpan material was compacted and graded to a 1% slope. Spawning gravels were also graded to 1% with a meandering low flow channel. Eight arrays of large woody debris were then placed in pools to give fish sheltered resting areas. Larger rocks were added to help stabilize streambed materials during high stream flow events.

Culvert Replacement

An unnamed tributary stream just downstream from the dam was also inaccessible to fish because it was perched several hundred feet above the stream channel. This culvert was replaced by a fish passable culvert installed at the new channel grade.

Flow Bypass System

A flow bypass system was installed to control lake levels and moderate winter flood flows. When needed, some stream flow can be directed around the dam structure and through an aluminum slide gate into two 24” overflow pipes. A gangway bridge allows access to the control valve.

Remote Site Incubator

Two black barrels are remote site incubators used to reintroduce chum salmon to Terrell Creek. Chum eggs are placed into the barrels in the winter and thrive with water piped through the dam and under the streambed. Developed juvenile salmon smolts will leave the incubators in the spring and migrate to the Birch Bay and then the ocean.

Riparian Planting

Native trees and shrubs were planted along Terrell Creek to speed the growth of a healthy streamside forest and provide forage and cover for fish.